Craigslist is a mess. Buyers that flake or waste your time with ridiculous lowball offers (or attempt flat out scams), and id have a problem buying without stubhub's buyer protections.
ISU will know if someone sells phony tickets noone can sell a ticket that isn't legit and get away with it and still buy again, and in order to forward to yourself you need to be the purchaser. Stubhub has very few scammers however you pay for the potential of a scam by basically giving them a 33% markup of what the seller receives. Shocked you've had bad experiences I've sold tickets to probably 500 people off craigslist not just ISU tix over the years and haven't had 1 scammer. I've ignored maybe 2-3 sketchy emails (like offering a massage lol) and thats it.
Craigslist is all about finding people who are legit and aren't greedy. If you find a good deal generally speaking meet the guy ASAP because someone will want them too and be willing to meet sooner if you wait. Downsides to CL is its like a flea market with idiot sellers who think their stuffs worth more than it is or buyers who think they can pay 20 cents on the dollar for market value, and people use the free advertising to ask for stupid prices in hopes someone bites. They know Stubhub is always there to get less money so they go on it hoping to make more. The CyHawk game has clearly brought out a lot of those sellers who want to pay for next years seats with this one game, can't really blame them.
When I sell tickets for ISU on CL 50% of the fans live not in Des Moines and like to meet at the game. ITs always good to have enough tickets that you can promise to hold them for the person and put them to the side and have more to keep on selling. 90% of ISU buyers are not flakes and are pretty legit, and if they do flake there is often a reason. (Like prices drop big time in the 2 weeks between you agreeing to meet at the game and the game.)
The only bad people to be avoided IMO are other sellers who are looking to buy your tickets and make money themselves those people get you to a parking lot and try to get a lower deal than agreed to. But those guys are the parking lot crackheads who show up with I need ticket signs hoping gullible fans will sell them their extras for peanuts. ******* hate those sellers its a shame that for every legit fan with extras or non greedy serious seller there is one of them trying to rip someone off.